Our laboratory has recently established that membrane antigens and receptors can be displaced vertically to the membrane plane, upon changes in the lipid fluidity. The consequent passive modulation of antigenic expression and receptor function constitutes the first part of this project, where the effect of lipid fluidity on the exposure of blood-group antigens and lymphocyte markers, as well as on the availability and kinetics of the receptors to insulin and transferrin, will be studied in detail. Augmentation of immunogenicity of tumor cells by exposure of cryptic tumor-associated antigens will be the main objective of this project. Tumor immunization with lipid-modified syngeneic tumor cells will thoroughly be investigated, in an attempt to devise a new active immunotherapy tool for human cancer. The converse possiblity that over-exposure of membrane proteins can evoke an autoimmune response will be studied in experimentally induced autoimmune hemolytic anemia.